(1) Field of the Invention
This invention relates to a power-supply control system for a portable data processor and a method for driving the same. More particularly, the invention relates to a power-supply control system for a portable data processor having a suspended operation mode and a normal operation mode, in order to increase efficiency.
(2) Description of the Related Art
Portable data processors such as notebook size personal computers or small-sized word processors are widely used. Conventional portable data processors require a battery, which may be a charging battery or a general battery, and a power-supply control system to increase the life span of the battery by efficiently controlling power consumption.
FIG. 1 is a circuit diagram of a known power-supply control system for a conventional portable data processor. The power-supply control system includes a main battery 20; a back-up battery 30; diode D12 connected between the output terminals of the main battery 20 and the back-up battery 30; diode D11 and resistance R11 connected in series between the anode and cathode of diode D12; a power switch S11 for selectively connecting the main battery 20 with a regulator 40 and a DC/DC converter 70; a suspend/resume converting switch S12 for selectively operating a suspend/resume signal generator 50; a power management system 60 having an input terminals connected to the output of suspend/resume signal generator 50 and the regulator 40; a suspend logic circuit 80 which receives the output of DC/DC converter 70; and a switch 90 for selectively connecting the DC/DC converter 70 and with a normal logic circuit 100.
In operation, if a user turns on the power-on switch S11 and the main battery 20 is installed in the system, power is applied to the regulator 40 and DC/DC converter 70 from the main battery 20. If the main battery 20 is not installed in the system or is unable to provide adequate power, power is applied to the regulator 40 and DC/DC converter 70 from the back-up battery 30. Regulator 40 ensures that a constant voltage is applied to the power management system 60.
The power management system outputs the power-on signal +5 VON to enable the DC/DC converter 70 and suspend signal SPEND to operate switch 90.
The DC/DC converter 70 adjusts and stabilizes the direct current voltage supplied by the main battery 20 or the back-up battery 30, and then supplies a stable system voltage to the suspend only logic circuit 80 for suspended operation and to normal logic circuit 100 for normal operation.
A user desiring to resume work on the portable data processor at a later time may operate the suspend/resume converting switch S12 to cause the power management system 60 to output a suspend signal SPEND to turn off the switch 90.
Alternatively, the power management system 60 may sense that the user has not worked on the portable data processor for a predetermined period of time. If so, the power management system 60 outputs the suspend signal SPEND signal to turn off the switch 90.
If switch 90 is turned off, the DC voltage applied to the normal logic circuit 100 from the DC/DC converter 70 is cut off, and the portable data processor operates in a suspend mode. Accordingly, such a system may reduce power consumption by the amount of the driving power of the normal logic circuit 100.
If the suspend/resume converting switch S12 is operated when the user resumes work on the portable data processor, a resume signal is produced by the suspend/resume signal generator 50, and output to the power management system 60. The power management system 60 then disengages the suspend signal SPEND so that the switch 90 is turned on. Once the switch 90 is turned on, the DC current is applied to the normal logic circuit 100 to operate the portable data processor normally.
In this arrangement, the power-supply control system of the conventional portable data processor drives the suspend only logic circuit 80 in a suspend mode, and drives the suspend only logic circuit 80 and normal logic circuit 100 in a normal operation mode. Thus, the overall efficiency of the data processor is reduced.
Further, the conventional power-supply control system attempts to operate in the normal mode, even if the main battery 20 is not connected, or if the main battery 20 and the back-up battery 30 are completely discharged. The life span of the main battery 20 and back-up battery 30 may thus be reduced by overdischarging.
U.S. Pat. No. 5,230,074, issued on Jul. 20, 1993 and entitled "Battery Operated Computer Power Management System," discloses a technique using a second DC/DC converter in addition to a main DC/DC converter. This second DC/DC converter is a step-up DC/DC converter for supplying a system voltage from a backup battery which provides a voltage lower than the system voltage. This is unlike the main DC/DC converter, which is a step-down converter. The second DC/DC converter enables adequate power to be supplied to a dynamic random access memory when the main battery is removed for replacement. This patent does not teach the use of a second DC/DC converter which is capable of operation in conjunction with the main battery in an alternate power conservation mode.